Frog sciatic nerves have been exposed to continuous wave (CW) and pulse microwave radiation. Rate of fatigue or loss of vitality (the ability of the nerve to continue firing under rapid stimulation) was increased in the nerve exposed to 2.45 GHz at a specific absorption rate of 10 mW/g. In order to determine if sine-wave modulated microwaves had an increasing effect on ionic transport as reported in the literature to occur in chick brain, frog sciatic nerves were exposed to 2.45GHz microwaves sine-wave modulated at 8, 16, and 32 Hz. It was found that a 50 mW/g specific absorption rate was required to obtain a loss in vitality with this form of radiation. This result suggests that the nerve vitality is nonlinear with respect to microwave intensity. This type of nonlinear behavior would be expected if the neural membrane is acting as a diode-like detector of the microwave field. Additional nerves were exposed 2.45 GHz (CW) microwaves at SARs of 4, 7, and 10 mW/g at a temperature of 24 degrees C. The increase in rate of fatigue was significant at 7 and 10 mW/g but not at 4 mW/g. The effect occurred after approximately 20 minutes of exposure at 10 mW/g and 1 hour at 7 mW/g. Nerves were exposed to 10 mW/g at ambient temperatures of 20 degrees C and 28 degrees C. The refractory period was shortened at 28 degrees C, and the latency was increased at 20 degrees C.